1. Field of the Invention
The present invention relates to an ignition timing controller for an internal combustion engine and, more particularly, to a pressure-responsive ignition timing controller for a supercharged internal combustion engine.
2. Description of the Prior Art
Ignition timing controllers each responsive to changes of pressure present in that part of the intake passage of a supercharged internal combustion engine which is adjacent to the engine throttle valve to control the ignition timing of the engine were already known, for example, from Japanese patent publication No. 42-8248, published Apr. 7, 1967, and Japanese patent publication No. 46-19213 corresponding to U.S. Pat. No. 3,612,019 issued Oct. 12, 1971 Hisaji Okamoto et al. The ignition timing controller of the above-mentioned class is mounted on a housing of a distributor, which is operative to distribute high voltage current to respective spark plugs of engine cylinders, and cooperates with the conventional ignition signal generator in the distributor housing to control the ignition timing of the engine. For this purpose, the ignition timing controller is provided with a spring-loaded diaphragm which is responsive to the pressure change. In the ignition timing controllers disclosed in the above-mentioned publications, the springs by which the diaphragm is spring-loaded, are disposed on the opposite sides of the diaphragm. Due to this spring arrangement, it is very difficult to conduct a fine adjustment of the ignition timing characteristic of the ignition timing controller, i.e., to finely adjust the pre-set loads of the springs on the diaphragm after the ignition timing controller has once been mounted on the distributor housing.